[SeaBIOS] [PATCH v3 2/3] smp: refactor present CPU APIC ID detection and counting

[Kevin O'Connor]

On Fri, Aug 05, 2016 at 12:47:28PM +0200, Igor Mammedov wrote:
> From: Kevin O'Connor <kevin at koconnor.net>
> 
> Signed-off-by: "Kevin O'Connor" <kevin at koconnor.net>
> Signed-off-by: Igor Mammedov <imammedo at redhat.com>
> ---
> v2:
>   * s/count_cpu/apic_id_init/
>   * call apic_id_init() after sending SIPI,
>     it will be needed for switching BSP into x2APIC mode
> ---
>  src/fw/smp.c | 32 +++++++++++++++++++-------------
>  1 file changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/src/fw/smp.c b/src/fw/smp.c
> index 719d51d..2c5670c 100644
> --- a/src/fw/smp.c
> +++ b/src/fw/smp.c
> @@ -55,24 +55,32 @@ int apic_id_is_present(u8 apic_id)
>      return !!(FoundAPICIDs[apic_id/32] & (1ul << (apic_id % 32)));
>  }
>  
> +static int
> +apic_id_init(void)
> +{
> +    CountCPUs++;
> +
> +    // Track found apic id for use in legacy internal bios tables
> +    u32 eax, ebx, ecx, cpuid_features;
> +    cpuid(1, &eax, &ebx, &ecx, &cpuid_features);
> +    u8 apic_id = ebx>>24;
> +    FoundAPICIDs[apic_id/32] |= 1 << (apic_id % 32);
> +
> +    return apic_id;
> +}
> +
>  void VISIBLE32FLAT
>  handle_smp(void)
>  {
>      if (!CONFIG_QEMU)
>          return;
>  
> -    // Detect apic_id
> -    u32 eax, ebx, ecx, cpuid_features;
> -    cpuid(1, &eax, &ebx, &ecx, &cpuid_features);
> -    u8 apic_id = ebx>>24;
> +    // Track this CPU and detect the apic_id
> +    int apic_id = apic_id_init();
>      dprintf(DEBUG_HDL_smp, "handle_smp: apic_id=%d\n", apic_id);
>  
>      smp_write_msrs();
>  
> -    // Set bit on FoundAPICIDs
> -    FoundAPICIDs[apic_id/32] |= (1 << (apic_id % 32));
> -
> -    CountCPUs++;
>  }
>  
>  // Atomic lock for shared stack across processors.
> @@ -93,11 +101,6 @@ smp_scan(void)
>          return;
>      }
>  
> -    // mark the BSP initial APIC ID as found, too:
> -    u8 apic_id = ebx>>24;
> -    FoundAPICIDs[apic_id/32] |= (1 << (apic_id % 32));
> -    CountCPUs = 1;

Now that scan_smp() is called from the resume path, we do have to
initialize CountCPUs here.  Probably best to not move the updating of
CountCPUs into apic_id_init().

-Kevin